1. Field of the Invention
The invention relates to video processing and more particularly relates to a video processing method and apparatus with residue prediction.
2. Description of the Related Art
With rapid development of video processing, including decoding and encoding technology, higher compression ratios so that video can be stored and broadcasted more efficiently are being demanded. Generally, a video sequence is composed of a series of video frames containing spatial and temporal redundancies, which may be encoded by many block-based video-coding standards, e.g., MPEG-1/2/4, H.264, etc., without significantly sacrificing video quality.
As for the H.264 standard, spatial correlations between adjacent pixels or blocks may be removed by introducing intra-frame prediction methods. Thus, allowing a current block to be predicted from reconstructed neighboring pixels of previous blocks within a current video frame. Due to intra-frame prediction, each block is reconstructed for encoding subsequent neighboring blocks. Further, inter-frame prediction (i.e., motion compensation prediction) has been adopted to reduce temporal redundancies between successive video frames by using motion vectors which indicate the displacement of a moving object from a current block in the current video frame to a corresponding displaced block in a reference video frame. The difference between the current block and the corresponding displaced block is referred to as residues. The reconstructed video frame is used for intra-frame prediction of subsequent neighboring blocks within the current video frame and inter-frame prediction of subsequent video frames.
In most cases, intra-frame prediction is selected only when a scene change occurs or significant motion exists. However, intra-frame prediction possesses some merits in image regions with high geometric features and provides error resilience. In some research studies, motion compensation can be combined with the intra-frame prediction. C. Chen and K. Pang, “Hybrid Coders with Motion Compensation,” Multidimensional Systems and Signal Processing, May. 1992 describes that some spatial correlations are among motion compensation residues. Also, B. Tao and M. Orchard, “Gradient-Based Residual Variance Modeling and Its Applications to Motion-Compensated Video Coding,” IEEE Transactions on Image Processing, January 2001 mentions that the spatial correlations show some geometric features. Further, the method described by K. Andersson in “Combined Intra Inter Prediction Coding Mode,” VCEG-AD11, 30th VCEG meeting, October 2006 proposes a direct combination of intra-frame prediction and inter-frame prediction. Another method disclosed by S. Chen, L. Yu in “Re-prediction in Inter-prediction of H.264,” VCEG-AG20, 33rd VCEG meeting, October 2007 uses the residues of neighboring blocks in a current video frame to predict the motion compensation residues of a current block within the current video frame. Nevertheless, no apparent improvement in coding efficiency is specified according to the prior art.
Therefore, it is crucial to provide an innovative algorithmic technique for video coding capable of utilizing residual correlations between neighboring blocks to predict the current block to improve coding efficiency or enhancing video quality.